zig/lib/std/heap/logging_allocator.zig
2021-01-08 16:54:56 -05:00

108 lines
3.8 KiB
Zig

// SPDX-License-Identifier: MIT
// Copyright (c) 2015-2021 Zig Contributors
// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
// The MIT license requires this copyright notice to be included in all copies
// and substantial portions of the software.
const std = @import("../std.zig");
const Allocator = std.mem.Allocator;
/// This allocator is used in front of another allocator and logs to the provided stream
/// on every call to the allocator. Stream errors are ignored.
/// If https://github.com/ziglang/zig/issues/2586 is implemented, this API can be improved.
pub fn LoggingAllocator(comptime Writer: type) type {
return struct {
allocator: Allocator,
parent_allocator: *Allocator,
writer: Writer,
const Self = @This();
pub fn init(parent_allocator: *Allocator, writer: Writer) Self {
return Self{
.allocator = Allocator{
.allocFn = alloc,
.resizeFn = resize,
},
.parent_allocator = parent_allocator,
.writer = writer,
};
}
fn alloc(
allocator: *Allocator,
len: usize,
ptr_align: u29,
len_align: u29,
ra: usize,
) error{OutOfMemory}![]u8 {
const self = @fieldParentPtr(Self, "allocator", allocator);
self.writer.print("alloc : {}", .{len}) catch {};
const result = self.parent_allocator.allocFn(self.parent_allocator, len, ptr_align, len_align, ra);
if (result) |buff| {
self.writer.print(" success!\n", .{}) catch {};
} else |err| {
self.writer.print(" failure!\n", .{}) catch {};
}
return result;
}
fn resize(
allocator: *Allocator,
buf: []u8,
buf_align: u29,
new_len: usize,
len_align: u29,
ra: usize,
) error{OutOfMemory}!usize {
const self = @fieldParentPtr(Self, "allocator", allocator);
if (new_len == 0) {
self.writer.print("free : {}\n", .{buf.len}) catch {};
} else if (new_len <= buf.len) {
self.writer.print("shrink: {} to {}\n", .{ buf.len, new_len }) catch {};
} else {
self.writer.print("expand: {} to {}", .{ buf.len, new_len }) catch {};
}
if (self.parent_allocator.resizeFn(self.parent_allocator, buf, buf_align, new_len, len_align, ra)) |resized_len| {
if (new_len > buf.len) {
self.writer.print(" success!\n", .{}) catch {};
}
return resized_len;
} else |e| {
std.debug.assert(new_len > buf.len);
self.writer.print(" failure!\n", .{}) catch {};
return e;
}
}
};
}
pub fn loggingAllocator(
parent_allocator: *Allocator,
writer: anytype,
) LoggingAllocator(@TypeOf(writer)) {
return LoggingAllocator(@TypeOf(writer)).init(parent_allocator, writer);
}
test "LoggingAllocator" {
var log_buf: [255]u8 = undefined;
var fbs = std.io.fixedBufferStream(&log_buf);
var allocator_buf: [10]u8 = undefined;
var fixedBufferAllocator = std.mem.validationWrap(std.heap.FixedBufferAllocator.init(&allocator_buf));
const allocator = &loggingAllocator(&fixedBufferAllocator.allocator, fbs.writer()).allocator;
var a = try allocator.alloc(u8, 10);
a = allocator.shrink(a, 5);
std.testing.expect(a.len == 5);
std.testing.expectError(error.OutOfMemory, allocator.resize(a, 20));
allocator.free(a);
std.testing.expectEqualSlices(u8,
\\alloc : 10 success!
\\shrink: 10 to 5
\\expand: 5 to 20 failure!
\\free : 5
\\
, fbs.getWritten());
}